/*
 * Port from rhash. origin license:
 * sha256.c - an implementation of SHA-256/224 hash functions
 * based on FIPS 180-3 (Federal Information Processing Standart).
 *
 * Copyright: 2010-2012 Aleksey Kravchenko <rhash.admin@gmail.com>
 *
 * Permission is hereby granted,  free of charge,  to any person  obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction,  including without limitation
 * the rights to  use, copy, modify,  merge, publish, distribute, sublicense,
 * and/or sell copies  of  the Software,  and to permit  persons  to whom the
 * Software is furnished to do so.
 *
 * This program  is  distributed  in  the  hope  that it will be useful,  but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  Use this program  at  your own risk!
 */
#include <bela/hash.hpp>
#include "hashinternal.hpp"

namespace bela::hash::sha256 {
//
constexpr const uint32_t k256[64] = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98,
    0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8,
    0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819,
    0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7,
    0xc67178f2
    //
};

/* The SHA256/224 functions defined by FIPS 180-3, 4.1.2 */
/* Optimized version of Ch(x,y,z)=((x & y) | (~x & z)) */
#define Ch(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
/* Optimized version of Maj(x,y,z)=((x & y) ^ (x & z) ^ (y & z)) */
#define Maj(x, y, z) (((x) & (y)) ^ ((z) & ((x) ^ (y))))

#define Sigma0(x) (ROTR32((x), 2) ^ ROTR32((x), 13) ^ ROTR32((x), 22))
#define Sigma1(x) (ROTR32((x), 6) ^ ROTR32((x), 11) ^ ROTR32((x), 25))
#define sigma0(x) (ROTR32((x), 7) ^ ROTR32((x), 18) ^ ((x) >> 3))
#define sigma1(x) (ROTR32((x), 17) ^ ROTR32((x), 19) ^ ((x) >> 10))

/* Recalculate element n-th of circular buffer W using formula
 *   W[n] = sigma1(W[n - 2]) + W[n - 7] + sigma0(W[n - 15]) + W[n - 16]; */
#define RECALCULATE_W(W, n) ((W)[n] += (sigma1((W)[((n)-2) & 15]) + (W)[((n)-7) & 15] + sigma0((W)[((n)-15) & 15])))

#define ROUND(a, b, c, d, e, f, g, h, k, data)                                                                         \
  {                                                                                                                    \
    unsigned T1 = (h) + Sigma1(e) + Ch(e, f, g) + (k) + (data);                                                        \
    (d) += T1, (h) = T1 + Sigma0(a) + Maj(a, b, c);                                                                    \
  }
#define ROUND_1_16(a, b, c, d, e, f, g, h, n) ROUND(a, b, c, d, e, f, g, h, k256[n], W[n] = bela::frombe(block[n]))
#define ROUND_17_64(a, b, c, d, e, f, g, h, n) ROUND(a, b, c, d, e, f, g, h, k[n], RECALCULATE_W(W, n))

void Hasher::Initialize(HashBits hb_) {
  hb = hb_;
  static constexpr const uint32_t SHA256_H0[8] = {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
                                                  0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};
  /* Initial values from FIPS 180-3. These words were obtained by taking
   * bits from 33th to 64th of the fractional parts of the square
   * roots of ninth through sixteenth prime numbers. */
  static constexpr const uint32_t SHA224_H0[8] = {0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939,
                                                  0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4};
  if (hb == HashBits::SHA256) {
    length = 0;
    digest_length = sha256_hash_size;
    memcpy(this->hash, SHA256_H0, sizeof(this->hash));
    return;
  }
  length = 0;
  digest_length = sha224_hash_size;
  memcpy(this->hash, SHA224_H0, sizeof(this->hash));
}

/**
 * The core transformation. Process a 512-bit block.
 *
 * @param hash algorithm state
 * @param block the message block to process
 */
static void sha256_process_block(unsigned hash[8], unsigned block[16]) {
  unsigned A;
  unsigned B;
  unsigned C;
  unsigned D;
  unsigned E;
  unsigned F;
  unsigned G;
  unsigned H;
  unsigned W[16];
  const unsigned *k;
  int i;

  A = hash[0], B = hash[1], C = hash[2], D = hash[3];
  E = hash[4], F = hash[5], G = hash[6], H = hash[7];

  /* Compute SHA using alternate Method: FIPS 180-3 6.1.3 */
  ROUND_1_16(A, B, C, D, E, F, G, H, 0);
  ROUND_1_16(H, A, B, C, D, E, F, G, 1);
  ROUND_1_16(G, H, A, B, C, D, E, F, 2);
  ROUND_1_16(F, G, H, A, B, C, D, E, 3);
  ROUND_1_16(E, F, G, H, A, B, C, D, 4);
  ROUND_1_16(D, E, F, G, H, A, B, C, 5);
  ROUND_1_16(C, D, E, F, G, H, A, B, 6);
  ROUND_1_16(B, C, D, E, F, G, H, A, 7);
  ROUND_1_16(A, B, C, D, E, F, G, H, 8);
  ROUND_1_16(H, A, B, C, D, E, F, G, 9);
  ROUND_1_16(G, H, A, B, C, D, E, F, 10);
  ROUND_1_16(F, G, H, A, B, C, D, E, 11);
  ROUND_1_16(E, F, G, H, A, B, C, D, 12);
  ROUND_1_16(D, E, F, G, H, A, B, C, 13);
  ROUND_1_16(C, D, E, F, G, H, A, B, 14);
  ROUND_1_16(B, C, D, E, F, G, H, A, 15);

  for (i = 16, k = &k256[16]; i < 64; i += 16, k += 16) {
    ROUND_17_64(A, B, C, D, E, F, G, H, 0);
    ROUND_17_64(H, A, B, C, D, E, F, G, 1);
    ROUND_17_64(G, H, A, B, C, D, E, F, 2);
    ROUND_17_64(F, G, H, A, B, C, D, E, 3);
    ROUND_17_64(E, F, G, H, A, B, C, D, 4);
    ROUND_17_64(D, E, F, G, H, A, B, C, 5);
    ROUND_17_64(C, D, E, F, G, H, A, B, 6);
    ROUND_17_64(B, C, D, E, F, G, H, A, 7);
    ROUND_17_64(A, B, C, D, E, F, G, H, 8);
    ROUND_17_64(H, A, B, C, D, E, F, G, 9);
    ROUND_17_64(G, H, A, B, C, D, E, F, 10);
    ROUND_17_64(F, G, H, A, B, C, D, E, 11);
    ROUND_17_64(E, F, G, H, A, B, C, D, 12);
    ROUND_17_64(D, E, F, G, H, A, B, C, 13);
    ROUND_17_64(C, D, E, F, G, H, A, B, 14);
    ROUND_17_64(B, C, D, E, F, G, H, A, 15);
  }

  hash[0] += A, hash[1] += B, hash[2] += C, hash[3] += D;
  hash[4] += E, hash[5] += F, hash[6] += G, hash[7] += H;
}

void Hasher::Update(const void *input, size_t input_len) {
  auto msg = reinterpret_cast<const uint8_t *>(input);
  size_t index = (size_t)length & 63;
  length += input_len;

  /* fill partial block */
  if (index != 0U) {
    size_t left = sha256_block_size - index;
    memcpy((char *)message + index, msg, (input_len < left ? input_len : left));
    if (input_len < left) {
      return;
    }

    /* process partial block */
    sha256_process_block(hash, (unsigned *)message);
    msg += left;
    input_len -= left;
  }
  while (input_len >= sha256_block_size) {
    unsigned *aligned_message_block;
    if (IS_ALIGNED_32(msg)) {
      /* the most common case is processing of an already aligned message
      without copying it */
      aligned_message_block = (unsigned *)msg;
    } else {
      memcpy(message, msg, sha256_block_size);
      aligned_message_block = (unsigned *)message;
    }

    sha256_process_block(hash, aligned_message_block);
    msg += sha256_block_size;
    input_len -= sha256_block_size;
  }
  if (input_len != 0) {
    memcpy(message, msg, input_len); /* save leftovers */
  }
}
void Hasher::Finalize(uint8_t *out, size_t out_len) {
  size_t index = ((unsigned)length & 63) >> 2;
  unsigned shift = ((unsigned)length & 3) * 8;

  /* pad message and run for last block */

  /* append the byte 0x80 to the message */
  message[index] &= bela::fromle(~(0xFFFFFFFFU << shift));
  message[index++] ^= bela::fromle(0x80U << shift);

  /* if no room left in the message to store 64-bit message length */
  if (index > 14) {
    /* then fill the rest with zeros and process it */
    while (index < 16) {
      message[index++] = 0;
    }
    sha256_process_block(hash, message);
    index = 0;
  }
  while (index < 14) {
    message[index++] = 0;
  }
  message[14] = bela::frombe((unsigned)(length >> 29));
  message[15] = bela::frombe((unsigned)(length << 3));
  sha256_process_block(hash, message);

  if (out != nullptr && out_len >= digest_length) {
    be32_copy(out, 0, hash, digest_length);
  }
}
} // namespace bela::hash::sha256
